Railroad warning sign



FIG. 1 is a front elevational view of a railroad warning sign showingour new design, it being understood that the broken lines are forillustrative purposes only and form no part of the claimed design;

FIG. 2 is a right side elevational view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a left elevational view thereof; and

FIG. 6 is a rear elevational view thereof.

The ornamental design for a railroad warning sign, as shown anddescribed.